struct SwsContext *pSwsCtx;
    AVFrame *video_frameBGR=NULL;
    video_frameBGR = av_frame_alloc();
    uint8_t *outBuff = NULL;
    int frameSize;
    {
        frameSize = avpicture_get_size(AV_PIX_FMT_BGR24, dec_ctx->width, dec_ctx->height);
        outBuff = (uint8_t*)av_malloc(frameSize);
        avpicture_fill((AVPicture 
 
*)video_frameBGR, outBuff, AV_PIX_FMT_BGR24, dec_ctx->width, dec_ctx->height);

        //ÉèÖÃͼÏñת»»ÉÏÏÂÎÄ  
        pSwsCtx = sws_getContext(dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
            dec_ctx->width, dec_ctx->height, AV_PIX_FMT_BGR24,
            SWS_BICUBIC, NULL, NULL, NULL);
    }
    cv::Mat img 
 
= cv::Mat::zeros(dec_ctx->height, dec_ctx->width, CV_8UC3);